Cerebrospinal fluid (CSF) is a clear liquid that surrounds the brain and spinal cord. Its role is to supply nutrients to these areas and to cushion the brain inside the skull.
The brain is covered in thin layers of tissue collectively called the dura mater, and CSF can escape through a tear in this tissue. The fluid may then leak from the nose or ears or into other parts of the body.
Also, CFS in the spine can leak into muscles and connective tissue surrounding the spinal column.
This article describes the causes and symptoms of a CSF leak. It also looks into how doctors diagnose and treat the issue and what to expect during recovery.
According to the Spinal CSF Leak Foundation, the most common symptom of a CSF leak is an upright headache — a headache that worsens when the head is in an upright position, as when a person is sitting or standing. These headaches usually improve when the person lies down.
Sometimes, the position of the head does not directly affect the severity of the headache. Instead, a person may experience a headache that worsens throughout the day.
An individual with a CSF leak may also notice clear, watery fluid draining from their nose or ears when they move their head, especially when bending forward. CSF may also drain down the back of the throat. People describe the taste as salty and metallic.
Other symptoms of a CSF leak include:
In adults, up to 90% of all CSF leaks result from head injuries.
Other causes of a CSF leak — in the skull or spine — include:
- an epidural injection
- an anesthetic injection
- a lumbar puncture
- brain tumors
- surgery on or around the base of the skull or spine
- structural abnormalities of the skull that have been present from birth
A doctor can use a number of tests to diagnose a CSF leak.
One test involves placing a sample of what the doctor suspects to be CSF discharge on a piece of filter paper. Once in contact with the paper, any CSF will separate from any blood or mucus. The result will form two distinct rings, called a "target" or "double ring" sign.
A healthcare professional can often identify CSF just by looking at a sample on a handkerchief or piece of gauze. Unlike mucus, which is thick and sticky, CSF is clear and watery.
Compared with mucus, CSF also has a high concentration of glucose. Checking the glucose levels in nasal discharge can help determine whether it contains CSF. Any sample of discharge that contains CSF can indicate a leak.
If a doctor suspects a CSF leak, they may order a CT or MRI scan to help confirm the diagnosis and locate the leak.
Treatment for a CSF leak depends on its severity and the cause. Some leaks respond to conservative treatment, while others require more invasive approaches.
Conservative treatments mainly focus on managing symptoms. These treatments may include:
- bed rest
- staying hydrated
- taking over-the-counter or prescription pain relief medication
- receiving intravenous caffeine infusions
A CSF leak that does not respond to conservative treatment may require more invasive approaches, such as those below.
An epidural blood patch
An epidural blood patch is a surgical procedure that involves using a person's own blood to patch tears in the dura mater.
During the procedure, the surgeon draws 5–25 milliliters of the person's blood, then injects it into a space just outside of the tear in the dura mater.
Epidural blood patches have high success rates but may not cure all types of CSF leaks.
In one 2016 study, researchers compared the success rates of epidural blood patches in 133 people with CSF leaks.
The researchers divided the participants into two groups based on the type of CSF leak. In one group, medical procedures had been responsible for the leaks. In the other group, there was no identified cause.
In 90.9% of the CSF leaks resulting from medical procedures, a single blood patch successfully treated each leak. In the other group, however, only 44.1% of the participants experienced full recovery after each having received a single patch. The rest of the group required additional treatment.
A doctor may recommend surgery if a person has:
- a CSF leak that does not improve with conservative treatment
- a severe CSF leak that is unlikely to heal on its own
- blood clotting in the brain or spinal cord
- herniated brain tissue that pushes into the ears or nose
Surgery involves suturing — or stitching— any tear to prevent further CSF leakage.
The specific approach depends on the location of the tear. For example, if a tear is in dura mater at the front of the head and causes the fluid to leak through the nose, the neurosurgeon may perform an endoscopic repair.
This is minimally invasive and involves inserting a thin, flexible tube called an endoscope through the nose, then passing tiny surgical tools through the tube to repair the tear.
If a tear causes CSF to drain from the ears, a neurosurgeon will need to perform open surgery. This involves making an incision in the scalp.
While an endoscopic approach presents less risk than traditional open surgery, the two methods have similar success rates.
A 2013 review compared the success rates of endoscopic and traditional surgical treatments of CSF leaks in the front of the skull. The review evaluated 71 studies, involving a total of 1,178 participants. The researchers found that each method successfully treated around 90% of CSF leaks.
A person should consider seeing a doctor if they experience any of the following symptoms of a CSF leak:
- a persistent runny nose
- drainage from the ears
- a headache that worsens when the head is upright
Also, anyone who experiences symptoms of a CSF leak following any of the following should seek medical attention:
- a head injury
- a recent epidural
- brain surgery
- spinal cord surgery
Recovery depends largely on the severity of the leak and the type of treatment.
People who receive conservative treatment can expect to stay in bed for at least 3 days. The doctor may recommend keeping the head elevated to encourage CSF drainage.
However, if the fluid drains too quickly, it can cause pockets of gas — called cranial aeroceles — to form inside the skull.
Other potential complications of a CSF leak include:
When a person has undergone surgical repair, they can expect to stay in the hospital for a few days or weeks. During this time, healthcare professionals will closely monitor their recovery and check for signs of complications, such as:
Early and accurate diagnosis of a CSF leak can lead to better treatment outcomes. It can also help prevent complications.
If symptoms do not improve within 10 days of conservative treatment, or if they return, a more invasive intervention may be necessary.
Both epidural blood patch and surgical procedures have relatively high success rates. However, they may not work. Even after surgery, some people continue to experience symptoms or disability resulting from CSF leakage.
A doctor or another healthcare professional who specializes in neurological conditions can discuss the options and recommend a course of treatment.
A CSF leak is a serious health issue. It involves this type of fluid escaping through a tear in the dura mater.
The symptoms of a CSF leak include fluid drainage from the ears or nose and a headache that worsens when the head is upright.
These leaks can result from head injuries, infections, and certain medical procedures. Although this issue may not cause alarming symptoms, it can lead to complications if the person does not receive appropriate treatment.
The right treatment varies, depending on factors specific to each person. Early conservative treatment usually involves bed rest and hydration. If symptoms do not improve within 10 days, the person may require a more invasive procedure, such as an epidural blood patch or surgery.